The ones at the top are static, if you scroll down, you will see the name of the animated .gif with the file extension .gif below the picture.
I have 74 Avatar pictures in that directory. The .gifs are near the bottom. You really want to download your own and use em. The ones that are included are weaksauce. Not very imaginative or anything.
You can always create your own as well using GIMP or Photoshop.
Here are some tuts. http://www.makeuseof.com/tag/how-to-...age-with-gimp/ http://comp3820.hubpages.com/hub/How...n-Animated-GIF
There are also websites that will either create an animated .gif from photo files you have, or split one into frames so you can edit and change. Google should sort you out. Like here http://www.gifmagic.com/